The present invention relates to a vacuum cleaner head which is especially useful for removing gravel and similar particulates from roofs and other surfaces. The invention will be described with respect to that particular application, although those skilled in the art will recognize the invention's applicability in other environments.
One of the most common types of flat roof construction for industrial, institutional and commercial buildings consists of a waterproof membrane, formed of alternate layers of a bitumen-saturated felt with layers of a bituminous sealant, and a loose covering of particulate material applied to the uppermost layer forming the waterproof membrane. The particulate material may, for example, be pea gravel, which ranges in size from 1/4 inch to 3/8 inch, or larger rock ranging from 1/2 inch to 5/8 inch.
From time to time, such roofs must be inspected, and where warranted, repaired. In order to accomplish these activities, the particulates, applied when the roof was constructed, together with dirt, grit and other materials which have accumulated with the passage of time must first be removed. One prior art system for removing such particulates, dirt and grit is described in my U.S. Pat. No. 3,955,236. This system involves vacuuming loose material off the roof, collecting and separating large particles from dust, filtering dust from the air and returning dust-free air to the atmosphere. The vacuum cleaner head used with this equipment, however, is of more or less conventional design.
While the method and equipment described in U.S. Pat. No. 3,955,236 is very effective in removing loose particulates, and substantially reduces the problem of dust generation described in the patent, it is not designed to remove partially embedded particulates and baked-on accumulations of dirt, grit, pollutants and the like.
The vacuum cleaner head of the present invention can be used to enhance the effectiveness of the system described in U.S. Pat. No. 3,955,236 by combining high velocity fluid jets, preferably water jets, with vacuum to accomplish the removal of partially embedded and baked-on particulates.
Others have recognized the advantage of combining vacuum and high velocity fluid jets to remove particulate matter from containers. See, for example, U.S. Pat. No. 3,959,845 which uses vacuum and high pressure fluid to remove particles from within mining cars. Also of interest are the teachings of U.S. Pat. No. 3,808,631 which disclose a shovel-like device for removing sludge from the surface of a liquid or from a floor such as a deck of a tanker.
The vacuum cleaner head disclosed in U.S. Pat. No. 3,959,845 is designed to be manipulated by a hydraulically actuated "back-hoe", and clearly cannot be hand-held nor slid along the surface to be cleaned.
The vacuum cleaner head illustrated in U.S. Pat. No. 3,808,631 while slidable along the surface to be cleaned, is clearly designed for the removal of a semi-fluid material, such as sludge. Because of the sharp, digging, leading edge of the shovel, it would not function well in the environment of a roof covered with gravel.
Other references of more general interest showing the state of the art include U.S. Pat. Nos. 4,137,600, 4,073,030, 3,963,515, 3,345,672, 2,916,761, and 2,646,889; British Pat. Nos. 1,288,763, 1,038,950 and 892,658; and French Pat. No. 2,264,510.